const names = ["a", "b", "c"]

const iterator = names[Symbol.iterator]()
console.log(iterator.next());
console.log(iterator.next());
console.log(iterator.next());
console.log(iterator.next());
console.log(iterator.next());

// Map/Set
const set = new Set()
set.add(10)
set.add(100)
set.add(1000)
